Pressure ulcers affect 1-3 million American adults. Prolonged pressure results in poor peripheral circulation and tissue hypoxia, and may cause significant tissue damage. As one of the adjunctive therapies, electrical stimulation (ES) is less labor intensive with lower costs compared to conventional therapies for ulcer treatment. However, ES parameters are often selected arbitrarily and treatment outcomes are evaluated by visible estimates of tissue mass and/or wound volume changes rather than intrinsic hemodynamic changes in ulcerous tissues. Early detection of pressure ulcers is the key for effective ulcer management and for reducing subsequent treatment costs. Since pressure ulcers usually originate from deep tissues attached to the bone (e.g., gluteal muscles surrounding the sacrum), measurement of deep tissue hemodynamics is essential for early diagnosis of ulcers and for optimization of ES treatment. However, no easy methods exist yet that are able to detect the early stages of ulcer development in deep tissues. A new advanced technology, near- infrared diffuse optics, can noninvasively monitor blood flow and oxygenation in deep tissues (up to several centimeters) with fiber-optic probes that gently contact the skin surface, and has recently been demonstrated in our preliminary studies. However, measurements of tissue hemodynamics using contact probes are not appropriate for ulcerous tissues that are prone to infection. This proposed project is to develop and validate a novel non-contact diffuse optical system (Aim 1) for early hemodynamic assessment of ulcer development in deep tissues. This non-contact system will completely avoid tissue deformation and potential infections induced by probe-tissue contact. This study will also integrate the non-contact system with an ES stimulator for treatment and therapeutic monitoring of pressure ulcers. After the integrated non-contact system is validated in healthy muscles and ES treatment parameters are optimized to maximize tissue hemodynamic responses to ES (Aim 2), the non-contact optical system will be used to detect blood flow and tissue oxygenation in gluteal muscles surrounding the sacrum in patients with or without pressure ulcers (stages I-IV) before, during and after ES treatments over 4 weeks (Aim 3). It is expected that measurement of deep tissue hemodynamics that affect tissue damage/healing will provide unique value for the early diagnosis of ulcer development, the objective optimization of ES parameters, and the longitudinal evaluation of ES treatment effects. Our long-term goal is to conduct extensive studies on statistically significant populations from multiple rehabilitation centers to translate and commercialize this innovative integrated system for the effective clinical management of pressure ulcers. Given the health burden of long-term care for pressure ulcers, this translational technology project has the potential to significantly advance our understanding of pressure ulcer development and treatment, ultimately leading to significant improvements in human health and substantial cost savings.